Carbonaceous reagent for carbonaceous binder used in the manufacture of fired carbon articles and carbon-bonded refractories

ABSTRACT

A carbonaceous reagent is provided for modifying a carbonaceous binder used in the manufacture of fired carbon articles and carbon-bonded refractories. The reagent serves to increase the carbonization yield of the binder. The reagent contains one or more functional groups each of which has one or more oxygen atom, has an atomic ratio of oxygen to carbon of from 0.05 to 0.30, and a carbonization yield per se of at least 50 percent.

United States Patent Kawai et al.

1 CARBONACEOUS REAGENT FOR CARBONACEOUS BINDER USED IN THE MANUFACTUREOF FIRED CARBON ARTICLES AND CARBON-BONDED REFRACTORIES Inventors:Yoshio Kawai; Kiro Asano; Kiyoshi Yamaki, all of Tokyo, Japan Assignee:Kureha Kagaku Kogyo Kabushiki Kaisha, Tokyo, Japan Filed: June 7, 1973Appl. No.: 367,449

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 3,238,116 3/1966 Hammer et al. 208/6 3,775,289 11/1973 Kishi etal 208/ Primary Examiner-Veronica OKeefe Attorney, Agent, or F irm-Flynn& Frishauf [57] ABSTRACT A carbonaceous reagent is provided formodifying a carbonaceous binder used in the manufacture of fired carbonarticles and carbon-bonded refractories. The reagent serves to increasethe carbonization yield of the binder. The reagent contains one or morefunctional groups each of which has one or more oxygen June 12, 1972Japan 47-57655 atom, has an atomic ratio of oxygen to carbon of from U SCl i I i I 208/6 208/44 0.05 to 0.30, and a carbonization. yield per seof at Int. Cl..::::: C10c 3/04 east 50 Percent- Field of Search 208/6,44 11 Claims, 3 Drawing Figures CD CD MIXING RATlO OF REAGENT TO BINDERPlTCH (WT./o)

PATENTEDFEBI 5 1865.713

SHEET 1 OF 2 FIG. 1

CARBONIZATION YIELD OF BINDER PITCH (WT. 03

MIXING RATIO OF REAGENT TO BINDER PITCH (WP/o) G *5 Lu '-'-':1: 10.15: o3 2t ZR 5;: 0Q E 010 E 99 9 2% 2 (IO 0 5005- 25 E4 E t a; 2& u-

HEAT TREATMENT TEMPERATURE FIG. 3

CARBONIZATION YIELD OF BINDER PITCH WT /o) ATOMIC RATIO O/C IN HEATTREATED OXIDIZED PITCH ll AR o A EoUs REAGENT FOR CARBONACEOUS BINDERUSED IN THE MANUFACTURE OF FinEn CARBON ARTICLES AND CAnBoN-BoNnEnREFRACTORIES This invention relates to carbonaceous reagents useful formodifying carbonaceous binders used in the manufacture of fired carbonarticles and Carbonbonded refractories, and to a method for forming saidreagents. The reagents are capable of increasing the carbonization yieldof said binders when said articles or refractories are fired, therebyproviding products of high density and great mechanical strength.

As used herein, the term carbonization yield of a binding material isdefined to mean an amount in percent by weight of a residual massderived from an original binding material when heated up to l,000C inincrements of C per minute in an atmosphere of inert gas.

Shaped and fired carbon articles, for example, carbon electrodes aremanufactured from coke, anthracite, graphite or carbon black finelydivided for use as a filler by adding to the filler a proper amount ofbinding material such as tar, pitch, phenolic resin or furan resin,kneading the mixture, and molding the kneaded mass, followed by firing.In a special case, these binding materials themselves are fired forcarbonization and may be made into carbon articles by the same processas described above with no use of fillers. In any case, the bindingmaterial, when fired, is generally carbon ized to an appreciably lowdegree and gives forth volatile matter possibly to make the resultingproduct undesirably porous, presenting difficulties in providingarticles of high density and great mechanical strength. To compensatefor such defects, it is customary practice to impregnate fired materialwith tar or pitch and again fire the impregnated mass so as to enablethe final product to increase in density and mechanical strength anddecrease in specific electric resistance.

To eliminate the above-mentioned troublesome procedure, it is consideredadvantageous to use a binder giving as high a carbonization yield aspossible. Therefore, the world tends to accept the so-called heavypitch, which provides a high carbonization yield. This heavy pitch hasan aromatic structure and a large molecular weight, and in consequenceindicates a high softening point and melt viscosity. However, theseproperties present great difficulties in kneading a mixture of heavypitch and filler and molding or extruding the kneaded mass, imposingconsiderable limitation on application of the heavy pitch.

On the other hand, study is in progress to add a small amount of reagentto pitch used as a binder. Attempts have been made to use, for example,dinitronaphthalene or 2,3-naphthoquinone as a reagent. However, such areagent itself is not only carbonized to a low extent and mostlyvolatilized when tired, but is also extremely expensive, failing to beput to industrial application in any way.

It is accordingly the object of this invention to provide an inexpensivereagent having a high carbonization yield per se and little soluble in abinding material preventing the softening point thereof from beingraised.

To this end, the reagent of this invention is prepared by oxidizing tar,pitch or coal by an oxidation process to introduce therein functionalgroups containing oxygen atoms to such an extent that the atomic ratioof oxygen to carbon in said reagent falls within the range of from 0.05to 0.30.

Other important objects and advantageous features of this invention willbe apparent from the following description and accompanying drawings,wherein the specific embodiments of the invention are set forth indetail.

FIG. 1 is a curve diagram showing the relationship between thecarbonization yield of a binder pitch and the mixing ratio of thereagent to the binder pitch used in Example 1;

FIG. 2 is a curve diagram showing the relationship between the atomicratios of oxygen to carbon and hydrogen to carbon in a reagent and thetemperature at which the reagent itself was heat-treated in Example 2;and

FIG. 3 is a curve diagram showing the relationship between thecarbonization yield of a modified binder pitch and the atomic ratio ofoxygen to carbon in the heattreated reagent of Example 2.

The reagent of this invention not only presents a high carbonizationyield itself but also is little soluble in a binder, preventing thebinder mixed with said reagent from being raised in the softening point.Further, the reagent acts as a sort of filler in the steps of kneading amixture of raw carbonaceous material and binder and molding or extrudingthe kneaded mass.

From such features, the reagent itself may be deemed as a special rawcarbonaceous material.

Moreover, with the reagent of this invention, functional groupsintroduced therein improve the wetting of the reagent to a binder,attaining an easy and homogeneous mixture thereof. When the kneaded massis fired, the functional groups of the reagent react with the binderprominently to increase the carbonization yield of the binder.Therefore, application of the reagent does not exert any harmful effecton the molding or extrusion of the kneaded mass, but facilitates themanufacture of carbon articles of high density and mechanical strengthand low specific electric resistance. The reagent of this invention canbe applied in manufacturing for not only the tired carbon artciles butalso refractories using a carbonaceous binder.

The raw material of the reagent of this invention may consist ofordinary tar or pitch, those obtained by polycondensation which isderived from heat-treatment and/or oxidation of petroleum. The reagentshould preferably be formed of a raw material of highly aromaticstructure so as to permit the easy introduction of functional groups insaid raw material by oxidation and enable the resultant reagent to havea low solubility and meltability and to have a high carbonization yielditself.

The raw material of the reagent may consist of not only theabove-mentioned types of tar and pitch but also finely ground coal. Thepreferred coals are anthracite and a bituminous type low in ash content,but any other kind of coal is acceptable.

Oxidation of the raw materials of the reagent is generally effected byvarious processes. Most convenient is the use of oxidizing gas, forexample, oxygen, ozone, air, sulfur trioxide, or nitrogen dioxide. It isalso possible to treat the raw materials of the reagent with anoxidizing aqueous solution of nitric acid, sulfuric acid, mixed acidthereof, hypochlorous acid or dichromic acid.

It does not matter whether the raw materials of the reagent are oxidizedin the form of powders, fibers, molten mass or solution. While notsubject to any particular limitation in temperature, the oxidation isgenerally carried out at to 400C so as to prevent undue oxidation. Ifthe raw materials are again heattreated for aging at lower temperaturesthan about 500C in an atmosphere of inert gas after the abovementionedoxidation, then the raw materials will present a prominent effect.

The oxidation causes the hydrocarbon molecules constituting the rawmaterials of the reagent to contain functional groups having an oxygenatom in the form of a carboxyl-, carbonyl- (of quinone, ketone oraldehyde type), hydroxy- (of phenol or alcohol type), ether-, or peroxygroup. Said oxidation also gives rise to polycondensation among tehydrocarbon molecules, and this causes the reagent prominently todecrease in solubility in binding materials and indicate a lowmeltability thereof. Depending on the kind of oxidizing agent used, someamount of, for example, nitro group, halogen group or sulfur group maysometimes be carried into the raw materials of the reagent, which,however, does not obstruct the function of the reagent.

The functional groups can be identified or their amounts can bequantitatively determined by the infrared spectrum analysis, elementaryanalysis or ordinary chemical analysis. The quantitative analysis of theindividual functional groups is difficult to carry out and alsounnecessary. It is sufficient to determine the atomic ratio of the totaloxygen atoms to the carbon atoms contained in the reagent. Theindispensable requisite for the reagent of this invention is that theatomic ratio of oxygen to carbon be defined within the range of 0.05 to0.30 or preferably 010 to 0.25. It has been found that where theabove-mentioned requisite is fully met, the atomic ratio of hydrogen tocarbon falls within the range of about 0.2 to 0.8. If the atomic ratioof oxygen to carbon decreases from 0.05, then the reagent will not fullydisplay its effect. Again where said ratio increases over 0.3, thereagent does not indicate any increased effect. Therefore, any processresulting in such excessively large atomic ratio of oxygen to carbon isnot only useless but also undesirably reduces the carbonization yield ofthe reagent per se.

The oxidation in producing the reagent gives rise to cross linking amongits molecules and minimizes the content of volatile matter, enabling thereagent to present a high carbonization yield. The reagent thus preparedhas a carbonization yield of at least 50 percent, generally ranging from60 percent to 92 percent.

As mentioned above, the reagent of this invention is substantiallyinsoluble in the binding materials and contains functional groups havingaffinity with the binding materials, and can be uniformly dispersedtherein due to good wettability. Further, the reagent undergoes littlechemical reaction with the binding materials at kneading and moldingtemperature, preventing the softening point or viscosity of the mixedbinding materials from being elevated and consequently causing themixture of filler and binder to be little reduced in moldability.

High temperature firing after molding gives rise to a chemical reactionbetween the reagent and binder, leading to not only the binding of themolecules of both constituents but also a chain reaction therebetween,thereby promoting polycondensation among the binder molecules.Accordingly, mere addition of a small amount of reagent to the binderconsiderably improves its carbonization yield, providing fired articlesof increased density, mechanical strength,,corrosion resistance andelectric conductivity.

While varying with the particle size distribution of the filler, themixing ratio of the filler to the binder and the kind of binder used, itmay be generalized that the reagent should preferably be added at theratio of l to 50 weight parts per weight parts of the binder. Aspreviously described, it is possible to apply the reagent itself as afiller, using very little filler or with its use entirely omitted. Insuch case, 2.5 to 100 weight parts of the binder are mixed with 50weight parts of the reagent. In a special case, carbon articles can beprepared from reagent and a binder (cf. Example 5).

The modifier of this invention has a variety of applications such ascarbon electrodes, carbon blocks, carbon articles used with mechanicalor electric machinery, amorphous carbon material to be stamped for useas lining, carbon paste for Soederberg electrodes and refractories.

The reagent of the present invention will be more fully understood byreference to the following examples.

EXAMPLE 1 Into the steam superheated to about 2,000C was introduced avapour of petroleum naphtha preheated to 350C. The vapour was thermallycracked for 0.003 second at l,l00C, followed by quenching, obtainingresidual tar with a yield of about 20 percent by weight in addition toethylene, acetylene, benzene and naphthalene. The tar was laterdistilled up to 300C at vacuum of 5 mml-lg to remove light weightcomponents, producing pitch in an amount about half the original weightof the tar.

The pitch indicated a hydrogen to carbon atomic ratio of 0.51 calculatedfrom measure of contents of hydrogen and carbon using the elementaryanalysis. The carbonization yield of said pitch was 64 percent. One gramof the pitch was put in a cylinder 1 cm in cross sectional area whichwas provided at the lower end with a nozzle 1 mm in diameter used in aFlow Tester. When the pitch was increasingly heated in increments of 10Cper minute at a pressure of 10 Kglcm the pitch indicated a softeningpoint of 218C as measured from the temperature at which the pitchcommenced to run out. The aforesaid hydrogen to carbon atomic ratio inthe pitch suggested that it consisted of a large amount of polycondensedaromatic components. This assumption was also confirmed by the IRspectrum and the NMR spectrum using carbon disulfide as a solvent.

After being crushed, the pitch was heated for oxidation to 250C byraising the temperature in increments of lC per minute in air containing3 percent by volume of nitrogen dioxide gas, obtaining a product havingthe properties given in Table 1 below.

Table 1 Properties of Oxidized Pitch Difficult to measure (above 400C)bg weight) Table l-Continued Properties of Oxidized Pitch Solubility inanthracene oil Carbonization yield of its own The instrumental analysissuch as the IR spectrum method and ordinary chemical analysisqualitatively proved that the oxidized pitch obtained containedcarboxy1-, carbonyl-, hydroxyland nitro groups, and oxygen of ethertype.

The oxidized pitch, that is, a reagent of this invention was pulverizedto such a particle size as passed the 100 Tyler mesh screen. The powdersobtained were mixed in various proportions with coal tar binder pitch ofwhich softening point and carbonization yield were 78C and 46 percentrespectively. Every 5 grams of the mixed mass was placed in a porcelaincrucible having a capacity of 30 c.c., and was heated to l,000C byraising temperature in increments of 5C per minute in an atmosphere ofnitrogen. FIG. 1 presents the carbonization yields of the binder pitchat different mixing ratios of the reagent to the binder pitch. Saidyield was calcu- EXAMPLE 2 The oxidized pitch obtained in Example 1having the properties set forth in Table 1 was heat-treated in anatmosphere of nitrogen at temperatures of 300, 400 500, 600, 700 and900C respectively. The elementary analysis was made of the each oxidizedpitch thus heat-treated to determine the atomic ratio of oxygen tocarbon and hydrogen to carbon in the pitch, the results being presentedin FIG. 2.

20 parts by weight of each heat-treated oxidized pitch were mixed witheighty parts by weight of the same petroleum pitch as used in Example 1.The carbonization yield of the petroleum pitch mixed with theheat-treated oxidized pitch was determined in the same manner as inExample 1, the results being set forth in FIG. 3. As apparent from FIGS.1, 2 and 3, the oxidized pitch heat-treated at temperatures of about 250to about 500C prominently elevated the carbonization yield of a binderpitch. Where, however, said heattreatment was effected at highertemperatures than 500C, the oxidized pitch thus heat-treated indicated asharp decline in the oxygen to carbon atomic ratio and in consequence anoticeable decrease in the ability to increase the carbonization yieldof the binder.

EXAMPLE 3 An oxidized pitch was prepared in the following manner.

Five hundred grams of blown asphalt having a penetration index of 10 to20, composed of 85.5 Weight percent carbon and 9.67 weight percenthydrogen, the hy drogen to carbon atomic ratio thereof being 1.36, weremelted at 380C. Nitrogengas was made to bubble through the moltenasphalt for 60 minutes at the rate of 2 l per minute for drydistillation, and further distilled 3 hours at 300C and vacuum of 10*mmHg, obtaining pitch having a softening point of about 180C with ayield of 29 percent by weight. The pitch was formed of 86.1 percentcarbon and 7.62 percent hydrogen and indicated a hydrogen to carbonatomic ratio of 1.06.

Those pulverized portions of the above-mentioned pitch which passedthrough the 10 0 Tyler mesh screen were used. Saidpulverized portionswere oxidized 3 hours at C in air containing 1.5 percent by volume ofozone. The oxidation was repeated in the same air by raising thetemperature to 260C in increments of 1C per minute. Final heat treatmentwas carried out 30 minutes at 350C in an atmosphere of nitrogen. Areagent obtained consisted of 76.1 percent carbon, 3.63 percent hydrogenand 20.1 percent oxygen, and indicated an oxygen to carbon atomic ratioof 0.20, a hydrogen to carbon atomic ratio of 0.57, and a carbonizationyield of 65 percent.

On the other hand, weight parts of calcined petrocoke having theparticle size distribution shown in Table 2 below and 33 weight parts ofan ordinary binder pitch were mixed to provide a control.

Table 2 Particle size distribution of calcined petrocoke by weightParticle sizes from 3 to 1.5 mm about 20 Particle sizes smaller than 1.5mm and over 200 Tyler mesh about 30 Particle sizes under 200 Tyler meshabout 50 To the above-mentioned calcined petrocoke, the binder pitch andthe reagent prepared from the aforesaid asphalt were mixed in theproportions given in Table 3 below. Every mixed mass was kneaded,extruded, baked and graphitized in succession. All the steps werecarried out as follows. Initially, the mixed mass was kneaded 40 minutesat to C and extruded at a pressure of 50 Kg/cm into rods each 25.4 mm indiameter and 100 mm long. The rods were buried in coke breeze and heatedto 700C in 50 hours and maintained 2 hours at said temperature. Later,the rods were heated to 2,600C in 3 hours and maintained 1 hour at saidtemperature to complete graphitization.

The kneading was carried out in a Z-type kneader having a capacity of lI. There was no difficulty in kneading and extruding the samples of thecontrol. The graphitized samples indicated the properties given in Table3 below as measured by the methods specified in the Japanese IndustrialStandards (JIS) R 7201 to R 7202.

Table 3 Composition of raw materials and properties of graphit'wedsamples The carbonization yield of the binder pitch shown in Table 3 wascalculated by deducting the residual amount of the calcined petrocokeand the reagent when they were graphitized singly.

EXAMPLE 4 Coal tar pitch composed of 92.30 wt. percent carbon, 4.50 wt.percent hydrogen, 0.20 wt. percent sulfur, 1.12 wt. percent nitrogen and1.88 wt. percent oxygen, in which the oxygen to carbon atomic ratio andthe hydrogen to carbon atomic ratio were 0.01 and 0.59 respectively, wasdry-distilled 1 hour at 380C while nitrogen gas was made to bubblethrough the pitch as in Example 3, and further distilled 1 hour at 270Cat vacuum to obtain with a yield of 52 percent a pitch having asoftening point of about 195C, containing 92.40 weight percent carbonand 3.67 weight percent hydrogen and indicating the hydrogen to carbonatomic ratio of 0.48.

Five hundred grams of those pulverized portions of the pitch whichpassed through the 100 Tyler mesh screen were placed in a l lflask. Airwas made to pass through the flask at the rate of l l per minute whilegently stirring the flask. The charged pitch was heated from roomtemperature to 150C in 10 minutes, further heated to 260C by raisingtemperature in increments of 1C per minute, and maintained 10 hours atthat LII temperature for oxidation. The oxidized pitch (reagent) thusobtained was formed of 71.9 weight percent carbon, 2.81 weight percenthydrogen and 23.64 weight percent oxygen, and indicated the oxygen tocarbon atomic ratio of 0.25 and the hydrogen to carbon atomic ratio of0.47, and had its own carbonization yield of 62 percent.

A plurality of mixed samples were prepared by mixing a filler formed ofpulverized pitch coke having a particle size distribution in whichparticle sizes ranging from 170 to 325 accounted for 25 percent byweight and those finer than 325 Tyler mesh occupied 75 percent byweight; a coal pitch binder having a softening point of 88C as measuredby the ring and ball method; and the aforesaid oxidized pitch in theproportions shown in Table 4. Each mixture was kneaded 30 minutes at150C, and the kneaded mass was charged in a metal mold 5 cm wide, 5 cmhigh and 20 cm long. The charge was molded at a pressure of 200 Kg/cm atl50C. The shaped samples were buried in coke breeze and heated to 700Cin 50 hours. Later, the samples were transferred to a graphitizingfurnace, heated to 2,700C in 4 hours and maintained 1 hour at thattemperature to complete graphitization. Thus were obtained samples ofgraphite electrode used in NaCl electrolysis. The samples presented theproperties given in Table 4.

Table 4 Composition of raw materials and properties of graphite samplesby weight):

Table 4-Continued Composition of raw materials and properties ofgraphite samples Properties of graphite sample:

Bulk density 1.60 1.62 Bending strength (Kglcm 180 220 S ecificresistance 90 85 Weight loss by electrolytic oxidation (mg/amp. hour)1.30 1.02

EXAMPLE Anthracite mined in North Vietnam was pulverized into fineparticles passing through the 100 Tyler mesh screen. The pulverized masswas heated to 230C by raising temperature in increments of 1C per minutein air containing 1.5 percent by volume of nitrogen dioxide gas andmaintained 30 minutes at that temperature for oxidation. The mass thustreated indicated, as measured by elementary analysis, the oxygen tocarbon atomic ratio of 0. l 4 and the hydrogen to carbon atomic ratio of0.34, and a carbonization yield of 85 percent. The oxidized anthracitewas fully insoluble in various types of pitch, and chemically analyzedto contain 5 X mol/g of carbonyl group, 2 X 10' moi/g of carboxyl groupand l X l0 moi/g of phenol type bydroxyl group.

The oxidized anthracite was used as both filler and reagent. Namely, 70parts by weight of powders of the oxidized anthracite were mixed with 30parts by weight of the pitch obtained by thermal decomposition ofnaphtha in Example 1. The mixed mass was kneaded at 250C and, aftercooling, pulverized into fine particles passing through the 200 Tylermesh screen. Water was added as a molding agent in the ratio of 5 partsby weight per 100 parts by weight of the powders. The mass was moldedinto a round column 30 mm in diameter and 30 mm long at room temperatureand a pressure of 300 Kg/cm The molded sample was buried in coke breezeand heated to 1,000C by raising temperature in increments of 100C perhour for carbonization to obtain a homogeneous compact article having avolumetric contraction coefficient of 35 percent, porosity of 14percent, compressive strength of 2,600 Kglcm Shore hardness of 110, bulkdensity of 1.39, and carbonization yield of about 90 percent.

EXAMPLE 6 The pitch obtained by thermal decomposition of naphtha inExample 1 was pulverized into fine particles passing through the 200Tyler mesh screen. One hundred grams of the powders obtained were mixedwith 1 [of 8 N water solution of nitric acid. Both materials werereacted 30 minutes at 40C. The reaction product was filtered and washedwith water. The resultant cake was dried 3 hours with hot air at 120C.Thus obtained reagent indicated the oxygen to carbon atomic ratio of0.069, the hydrogen to carbon atomic ratio of 0.42 and the carbonizationyield of 75 percent.

A mixture of said reagent and coal tar was used as a binder, and therewere prepared for trial samples of carbonaceous magnesia refractory,whose properties are presented in Table 5 below.

Table 5' Composition of raw materials and properties of refractorysamples samples (Kg/cm) What we claim is:

1. A method for preparing a carbonaceous reagent for acarbonaceousbinder used in the manufacture of tired carbon articles andcarbon-bonded refractories in order to increase the carbonization yieldof said binder, which comprises oxidizing a carbonaceous raw material ata temperature of from 15C. to 400C. with an oxidizing agent to providean atomic ratio of oxygen to carbon therein of from 0.05 to 0.3 0.

2. The method of claim 1, wherein an oxygen containing functional groupis introduced into said raw material by said oxidation.

3. A method according to claim 1, wherein the carbonaceous raw materialis one selected from the group consisting of a tar, a pitch and a coal.

4. A method according to claim 3, wherein the tar is coal tar orpetroleum tar.

5. A method according to claim 3, wherein the pitch is coal pitch orpetroleum pitch.

6. A method according to claim 3, wherein the coal is anthracite orbituminous coal.

7. A method according to claim 1, wherein the oxidizing agent is a gasselected from the group consisting of oxygen, ozone, air, sulfurtrioxide and nitrogen dioxide.

8. A method according to claim 1, wherein the oxidizing agent is anaqueous solution of an acid selected from the group consisting of nitricacid, sulfuric acid, a mixed acid of nitric and sulfuric acids,hypochlorous acid and dichromic acid.

9. A method for preparing a carbonaceous reagent for a carbonaceousbinder used in the manufacture of fired carbon articles andcarbon-bonded refractories in and carbon-bonded refractories, saidreagent increasing the carbonization yield of said binder, characterizedin that said reagent contains a functional group having an oxygen atom,has an atomic ratio of oxygen to carbon of from 0.05 to 0.30, and acarbonization yield per se of at least 50 percent.

11. A carbonaceous reagent according to claim 10, wherein the functionalgroup is selected from the group consisting of carboxyl-, carbonyl-,hydr0xy-, etherand peroxy groups.

1. A METHOD FOR PREPARING A CARBONACEOUS REAGENT FOR A CARBONACEOUSBINDER USED IN THE MANUFACTURE OF FIRED CARBON ARTICLES ANDCARBON-BONDED REFRACTORIES IN ORDER TO INCREASE THE CARBONIZATION YIELDOF SAID BINDER, WHICH COMPRISES OXIDIZING A CARBONACEOUS RAW MATERIAL ATA TEMPERATURE OF FROM
 2. The method of claim 1, wherein an oxygencontaining functional group is introduced into said raw material by saidoxidation.
 3. A method according to claim 1, wherein the carbonaceousraw material is one selected from the group consisting of a tar, a pitchand a coal.
 4. A method according to claim 3, wherein the tar is coaltar or petroleum tar.
 5. A method according to claim 3, wherein thepitch is coal pitch or petroleum pitch.
 6. A method according to claim3, wherein the coal is anthracite or bituminous coal.
 7. A methodaccording to claim 1, wherein the oxidizing agent is a gas selected fromthe group consisting of oxygen, ozone, air, sulfur trioxide and nitrogendioxide.
 8. A method according to claim 1, wherein the oxidizing agentis an aqueous solution of an acid selected from the group consisting ofnitric acid, sulfuric acid, a mixed acid of nitric and sulfuric acids,hypochlorous acid and dichromic acid.
 9. A method for preparing acarbonaceous reagent for a carbonaceous binder used in the manufactureof fired carbon articles and carbon-bonded refractories in order toincrease the carbonization yield of said binder, which comprisesoxidizing a carbonaceous raw material at a temperature of from 15* to400*C. with an oxidizing agent to introduce therein an oxygen-containingfunctional group, and heating the oxidized carbonaceous raw material foraging at a temperature of from 250* to 500*C. in an atmosphere ofinactive gas, whereby the atomic ratio of oxygen to carbon in thereagent falls within the range of from 0.05 to 0.30.
 10. A carbonaceousreagent for a carbonaceous binder used in the manufacture of firedcarbon articles and carbon-bonded refractories, said reagent increasingthe carbonization yield of said binder, characterized in that saidreagent contains a functional group having an oxygen atom, has an atomicratio of oxygen to carbon of from 0.05 to 0.30, and a carbonizationyield per se of at least 50 percent.
 11. A carbonaceous reagentaccording to claim 10, wherein the functional group is selected from thegroup consisting of carboxyl-, carbonyl-, hydroxy-, ether- and peroxygroups.